Scoping in Ruby blocks

locals_and_blocks.rb

def set_context(c)
  @context = c
end

def context
  @context
end


def with_context(cont, &block)
  original_cont = context
  set_context cont
  block.call
ensure
  set_context original_cont
end




set_context :base

foo = nil
with_context("hello") do
  foo = context.upcase
  bar = context.reverse
end




foo
# => "HELLO"
bar
# NameError: undefined local variable or method `bar' for main:Object